Systems And Methods For Lighting Spring Loaded Mechanical Key Switches

ABSTRACT

Systems and methods are disclosed that may be implemented to provide keycap lighting to a spring loaded mechanical key switch assembly using a light conductive structure, such as a light pipe, and without requiring a chassis housing of the mechanical key switch assembly to include a dedicated power-consuming light source mounted to or otherwise positioned at the location of the individual key switch assembly chassis housing. Additionally, the disclosed systems and methods may be implemented to use one or more common power-consuming light source/s to simultaneously provide key cap lighting to multiple such spring loaded mechanical key switch assemblies, for example, by feeding light to each key cap though a common light spreader and through an individual non-power consuming light pipe provided for each key switch assembly.

FIELD OF THE INVENTION

This invention relates generally to information handling systems and,more particularly, to systems and methods for lighting spring loadedmechanical key switches.

RELATED APPLICATIONS

The present application is related in subject matter to concurrentlyfiled patent application Ser. No. ______ entitled “SYSTEMS AND METHODSFOR IMPLEMENTING SPRING LOADED MECHANICAL KEY SWITCHES WITH VARIABLEDISPLACEMENT SENSING” by Casparian et al., which is incorporated hereinby reference in its entirety.

BACKGROUND OF THE INVENTION

As the value and use of information continues to increase, individualsand businesses seek additional ways to process and store information.One option available to users is information handling systems. Aninformation handling system generally processes, compiles, stores,and/or communicates information or data for business, personal, or otherpurposes thereby allowing users to take advantage of the value of theinformation. Because technology and information handling needs andrequirements vary between different users or applications, informationhandling systems may also vary regarding what information is handled,how the information is handled, how much information is processed,stored, or communicated, and how quickly and efficiently the informationmay be processed, stored, or communicated. The variations in informationhandling systems allow for information handling systems to be general orconfigured for a specific user or specific use such as financialtransaction processing, airline reservations, enterprise data storage,or global communications. In addition, information handling systems mayinclude a variety of hardware and software components that may beconfigured to process, store, and communicate information and mayinclude one or more computer systems, data storage systems, andnetworking systems.

Keyboards using spring loaded mechanical key switches are popular inputdevices for information handling systems, such as desktop and notebookcomputers. Keyboards that employ spring loaded mechanical key switchesare particularly popular among users of gaming applications, such as PCGamers. Examples of conventional mechanical key switches that areemployed in keyboards include Cherry MX Key Switches available from ZFElectronic Systems of Pleasant Prairie, Wis. These keys arespring-loaded and provide continuous tension throughout a downward keystroke, which has a total travel length of approximately 4 millimeters.The “make” connection for the mechanical switch is made at approximatelythe 2 millimeter downward key travel position (i.e., 50% downwardtravel). With a spring in place beneath the key, there is always tensionon the user's finger throughout the downward key stroke. After the“make” connection is made, no further electrical signals are created asthe key travels further downward a distance of another 2 millimeters asthe user continues to apply more downward pressure to the key.

Other types of information handling system keyboards include dome switchkeyboards that do not employ a mechanical switch but instead employs arubber-dome that overlies two electrically separated conductive layersat each key location. When a key is pressed by a user, the rubber domecontacts and compresses the two conductive layers together to cause anelectrical connection to be made between the two conductive layers atthe key location. The occurrence of this electrical connection creates adigital signal that is provided to a keyboard controller to indicatethat the particular key location has been pressed by the user. QWERTYstyle dome switch keyboards have been backlit using 10 to 12 edgemounted light emitting diodes (RGB or single color LEDs) that illuminatea polycarbonate light spreader layer located under and oriented parallelto the conductive layers of the dome switch keyboard. Light emanatesfrom the side surface of the light spreader and shines up in free spaceand through the intervening light-transmissive conductive layers of thekeyboard to backlight the keys which have light-transmissive charactersthat are laser-etched into the keycaps.

SUMMARY OF THE INVENTION

Disclosed herein are systems and methods that may be implemented toprovide spring loaded mechanical key switches having variabledisplacement sensing and reporting capabilities.

In one embodiment, such variable displacement sensing spring loadedmechanical key switches may be advantageously implemented as individualvariable displacement key switches of a keyboard for providing variabledisplacement output signals that may be processed by a controller forinput to a host processing device of an information handling system,such as a desktop or notebook computer. In a further embodiment, such akeyboard may be optimized or otherwise employed by a user for gamingapplications, such as PC games that execute on an information handlingsystem. In a further embodiment, the processed variable displacementoutput signals may be utilized by an information handling system as aproxy for (or indication of) the amount of pressure applied by a user toa key switch of a keyboard, e.g., for purposes of software applicationsand other software and/or firmware that utilize relative pressure(and/or absolute amount of pressure) applied by a user to a keyboard keyas a variable input signal.

In one particular implementation, a variable displacement sensing springloaded mechanical key switch may be configured to provide both a singledigital “make” connection signal (e.g., a single digital on/off signaloccurring at about a 50% downward travel of the keystroke), and aseparate variable displacement output signal/s (e.g., as one or moreanalog output signals that are representative of amount of downwarddisplacement currently being applied to the given key), each of whichmay be processed for input to host processing device of an informationhandling system such as desktop or notebook computer However, it will beunderstood that a variable pressure sensing spring loaded mechanical keyswitch may alternatively be configured to provide only variabledisplacement output signal/s, and without providing a separate digitalon/off output signal. Either way, a spring loaded mechanical key switchmay be provided that supports both a spring-loaded key feel and variabledisplacement sensing capability.

Also, disclosed herein are systems and methods that may be implementedin one embodiment to provide key cap lighting to a spring loadedmechanical key switch (e.g., via a light pipe) without requiring achassis housing of the mechanical key switch to include a dedicatedpower-consuming light source (e.g., such as a light emitting diode“LED”) mounted to or otherwise positioned at the location of theindividual key switch chassis housing. In a further embodiment, one ormore common power-consuming light source/s (e.g., such as one or commonLEDs) may be employed to simultaneously provide key cap lighting tomultiple spring loaded mechanical key switches without requiring adedicated power-consuming light source mounted to or otherwisepositioned at the chassis housing location of any of the individualspring loaded key switches, e.g., by feeding light to each key capthough a common light spreader and through an individual non-powerconsuming light pipe provided for each key switch.

Using the disclosed key cap lighting systems and methods, large savingsin keyboard power consumption and decreased keyboard assembly complexitymay be achieved for keyboards having multiple spring loaded mechanicalkey switches by employing a non-power consuming light source (e.g.,light pipe) to light each key switch cap rather than using a separatepower-consuming light source (e.g., such as a LED) mounted into or atthe location of each separate key switch chassis housing. In thisregard, overall keyboard power consumption may be reduced because thenumber of common power-consuming light sources that are employed tolight a given number of spring loaded mechanical key switches of akeyboard may be less than the total number of lighted mechanical keyswitches present in the keyboard. Thus, in one exemplary embodiment, itis possible that USB power from an information handling system may besufficient alone to light multiple (or all) spring loaded mechanical keyswitch caps of a keyboard (e.g., such as QWERTY keyboard) withoutrequiring use of an AC/DC adapter which would otherwise be required ifseparate power consuming light switches were required to be present ateach key switch. Moreover, the total number of power traces on thekeyboard PCB, the total number of individual power consuming lightsources in the keyboard, and the number of pins provided on each springloaded key switch chassis may also be advantageously reduced, savingassembly cost and complexity.

In one respect, disclosed is a keyboard system, including: a lightspreader component included of light transmissive material; one or morelight sources positioned to direct light into the light transmissivematerial of the light spreader component; and at least one spring loadedmechanical key switch assembly. The at least one spring loadedmechanical key switch assembly may itself include: a key switch chassishousing having a first end and a second end; a depressable key componentmovably received within the key switch chassis housing and having afirst end and a second end, the first end of the depressable keycomponent being movable between an extended position and a depressedposition relative to the first end of the key switch chassis housingwith the first end of the depressable key component being closer to thefirst end of the key switch chassis housing in the depressed positionthan in the extended position; a spring element configured to provide aresilient force to resist downward movement of the depressable keycomponent from the extended position to the depressed position; at leastone of digital signal circuitry configured to provide an on/off digitaloutput signal when the depressable key component is depressed downwardby a predetermined extent, variable displacement-sensing circuitryconfigured to detect displacement of the depressable key componentrelative to the key switch chassis housing and to provide one or morevariable displacement signals that vary in character based on the amountof displacement of the depressable key component between the extendedposition and the depressed position, or a combination thereof; and atleast one light conductive structure having first and second ends andextending from the second end of the key switch chassis housing to thefirst end of the key switch chassis housing, the first end of the lightconductive structure being positioned adjacent the first end of the keyswitch chassis housing and the second end of the light conductivestructure being positioned adjacent the second end of the key switchchassis housing. The second end of the light conductive structure may bepositioned to receive light from the light spreader component, the lightconductive structure may be configured to conduct light received fromthe light spreader to the first end of the light conductive structure,and the first end of the light conductive structure may be configured toemit the conducted light from the first end of the light conductivestructure.

In another respect, disclosed herein is a spring loaded mechanical keyswitch assembly, including: a key switch chassis housing having a firstend and a second end; a depressable key component movably receivedwithin the key switch chassis housing and having a first end and asecond end, the first end of the depressable key component being movablebetween an extended position and a depressed position relative to thefirst end of the key switch chassis housing with the first end of thedepressable key component being closer to the first end of the keyswitch chassis housing in the depressed position than in the extendedposition; a spring element configured to provide a resilient force toresist downward movement of the depressable key component from theextended position to the depressed position; at least one of digitalsignal circuitry configured to provide an on/off digital output signalwhen the depressable key component is depressed downward by apredetermined extent, variable displacement-sensing circuitry configuredto detect displacement of the depressable key component relative to thekey switch chassis housing and to provide one or more variabledisplacement signals that vary in character based on the amount ofdisplacement of the depressable key component between the extendedposition and the depressed position, or a combination thereof; and atleast one light conductive structure having first and second ends andextending from the second end of the key switch chassis housing to thefirst end of the key switch chassis housing, the first end of the lightconductive structure being positioned adjacent the first end of the keyswitch chassis housing and the second end of the light conductivestructure being positioned adjacent the second end of the key switchchassis housing. A second end of the light conductive structure may bepositioned to receive light from the light spreader component, the lightconductive structure may be configured to conduct light received fromthe light spreader to the first end of the light conductive structure,and the first end of the light conductive structure is configured toemit the conducted light from the first end of the light conductivestructure.

In another respect, disclosed herein is a method of operating one ormore key switch assemblies, including providing at least one springloaded mechanical key switch assembly. The at least one spring loadedmechanical key switch assembly may include: a key switch chassis housinghaving a first end and a second end; a depressable key component movablyreceived within the key switch chassis housing and having a first endand a second end, the first end of the depressable key component beingmovable between an extended position and a depressed position relativeto the first end of the key switch chassis housing with the first end ofthe depressable key component being closer to the first end of the keyswitch chassis housing in the depressed position than in the extendedposition; a spring element configured to provide a resilient force toresist downward movement of the depressable key component from theextended position to the depressed position; at least one of digitalsignal circuitry configured to provide an on/off digital output signalwhen the depressable key component is depressed downward by apredetermined extent, variable displacement-sensing circuitry configuredto detect displacement of the depressable key component relative to thekey switch chassis housing and to provide one or more variabledisplacement signals that vary in character based on the amount ofdisplacement of the depressable key component between the extendedposition and the depressed position, or a combination thereof; and atleast one light conductive structure having first and second ends andextending from the second end of the key switch chassis housing to thefirst end of the key switch chassis housing, the first end of the lightconductive structure being positioned adjacent the first end of the keyswitch chassis housing and the second end of the light conductivestructure being positioned adjacent the second end of the key switchchassis housing, the light conductive structure being configured toconduct light from the second end to the first end of the lightconductive structure. The first end of the light conductive structuremay be configured to emit the conducted light from the first end of thelight conductive structure, and the method may further include providinglight to the second end of the light conductive structure to cause thelight conductive structure to conduct and emit the light from the firstend of the light conductive structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side cut-away view of a spring loaded mechanicalkey switch assembly according to one exemplary embodiment of thedisclosed systems and methods.

FIG. 2A illustrates a side cut-away view of a spring loaded mechanicalkey switch assembly according to one exemplary embodiment of thedisclosed systems and methods.

FIG. 2B illustrates a side cut-away view of a spring loaded mechanicalkey switch assembly according to one exemplary embodiment of thedisclosed systems and methods.

FIG. 3 illustrates a side cut-away view of a spring loaded mechanicalkey switch assembly according to one exemplary embodiment of thedisclosed systems and methods.

FIG. 4 illustrates a side cut-away view of a spring loaded mechanicalkey switch assembly according to one exemplary embodiment of thedisclosed systems and methods.

FIG. 5 illustrates a side cut-away view of a spring loaded mechanicalkey switch assembly according to one exemplary embodiment of thedisclosed systems and methods.

FIG. 6 illustrates a side cut-away view of a spring loaded mechanicalkey switch assembly according to one exemplary embodiment of thedisclosed systems and methods.

FIG. 7 illustrates an exploded perspective view of a keyboard assemblyaccording to one exemplary embodiment of the disclosed systems andmethods.

FIG. 8 illustrates an overhead view of a light spreader componentaccording to one exemplary embodiment of the disclosed systems andmethods.

FIG. 9 illustrates a block diagram for a keyboard system according toone exemplary embodiment of the disclosed systems and methods.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 illustrates one exemplary embodiment of a spring loadedmechanical key switch assembly 10 configured to have variabledisplacement sensing capability. In this embodiment, key switch assembly10 includes a depressable key component 101 movably received within acomplementary dimensioned cavity 121 defined within key switch chassishousing 104. As shown, the depressable key component 101 may include akey cap 102 coupled to a shaft 103, plunger body 114, and plunger axle108. In one embodiment, the depressable key component 101 may bedepressable as single unit downward, e.g., as a single piece of plasticthat is received within cavity 121 of a plastic key switch housing 104,although other materials or combinations of materials are possible forboth depressable key switch component 101 and key switch housing 104,e.g., such as ceramic materials. Moreover, it is possible thatdepressable key component 101 may be made up of two or more assembledpieces.

Still referring to FIG. 1, key switch housing 104 of this embodimentincludes a displacement-sensing key well 150 having a plunger cavity 153defined therein into which plunger axle 108 is received when key cap 102is depressed downward by a force 190 as shown in FIGS. 2 and 4, e.g.,such as may be provided by a user's finger pressing the key cap 102. Inthis exemplary embodiment, an internal spring element in the form of acompression coil (or helical) spring 106 made of metal (e.g., such asstainless steel, spring steel, etc.) that is resting on the top of keywell 150 (e.g., by virtue of the diameter of coil spring 106 beinggreater than the internal diameter of plunger cavity 153 and theexternal diameter of plunger axle 108) may be provided as shown wrappedaround plunger axle 108 and configured to be compressed against the topof key well 150 when key cap 102 is depressed downward within key switchhousing chassis 104. In this manner, compression of internal spring 106provides a resilient force to resist the downward movement ofdepressable key component 101, and/or to urge depressable key component101 upward, within key switch housing chassis 104 such that there isalways tension on the user's finger, and to return the depressable keycomponent 101 to its non-depressed extended position. It will beunderstood that a spring loaded mechanical key switch assembly may beprovided with any alternative configuration of one or more springelements of metal or other suitably elastic material that is suitablefor providing a resilient force to resist the downward movement of adepressable key component, imparting tension to a user's finger duringdownward travel, and/or for urging a depressable key component 101 toreturn to its extended position, e.g., such as metal torsion springs,metal clock springs, etc. Moreover, it is also possible that more thanone spring element may be present.

Also shown in FIG. 1 is optional digital signal circuitry 109 that iscoupled to provide an on/off digital output signal 111 (e.g., to alegacy keyboard controller of an information handling system) whendepressable key component 101 is depressed downward by a predeterminedextent, e.g., such as when depressable key component 101 has beendepressed downward by about 50% of the total possible downward travellength of depressable key component 101. Although the spring loadedmechanical key switch assembly 10 of FIG. 1 is illustrated having bothdigital signal circuitry 109 and a displacement-sensing key well 150that includes variable displacement-sensing circuitry 152, it will beunderstood that in other embodiments a spring loaded mechanical keyswitch assembly may only be provided with a displacement-sensing keywell 150 that includes variable displacement-sensing circuitry 152, andnot provided with any digital signal circuitry 109 (e.g., mechanicalmake/break key contacts) such that the spring loaded mechanical keyswitch assembly is incapable of providing on/off digital output signals111.

As further shown in FIG. 1, displacement-sensing key well 150 includesvariable displacement-sensing circuitry 152 that is configured to detectand measure downward and/or upward key travel (and/or current position)of depressable key switch component 101 and to provide variabledisplacement signals 160 of varying character to displacementmeasurement circuitry 302 as shown. In this regard the character (e.g.,voltage, current, signal state, etc.) of variable displacement signals160 may vary according to the relative displacement of the depressablekey component between the extended position and the depressed positionof depressable key switch component 101 so as to indicate or to beindicative of the relative displacement of the depressable key componentbetween the extended position and the depressed position. Variabledisplacement-sensing circuitry 152 may be implemented using any type, orcombination of types, of sensor circuitry (e.g., one or more positionalsensors) that is suitable for detecting changes in downward traveldistance or depth of depressable key switch component 101 correspondingto downward displacement of a key cap 102. Example types of electricalsensor circuitry that may be employed include, but are not limited to,capacitive sensing circuitry, resistive sensing circuitry, opticalsensing circuitry, electrical field (E-field) or magnetic field(H-field) change detection circuitry, etc. In this regard, variabledisplacement-sensing circuitry 152 may be configured to detect andmeasure downward and/or upward key travel of depressable key switchcomponent 101 and provide variable displacement signals 160 throughoutthe entire downward and upward travel range of depressable key switchcomponent 101 independent of the operation of digital signal circuitry109 and conduction of on/off digital output signal 111.

However, variable displacement-sensing circuitry 152 may bealternatively configured to detect and measure downward and/or upwardkey travel of depressable key switch component 101 and provide variabledisplacement signals 160 only after depressable key component 101 hasbeen depressed downward by a predetermined extent (e.g., about 50% ofthe total possible downward travel length) to cause digital signalcircuitry 109 to provide an on/off digital output signal 111. In eitherembodiment, a user will be able to feel their finger continuing totravel beyond the 50% initial “make” digital signal point, and thevariable displacement-sensing circuitry 152 will continue to reportvarious plunger depth levels until 100% downward key travel has beenachieved.

FIG. 2A shows one exemplary embodiment of a spring loaded mechanical keyswitch assembly 100 having one exemplary embodiment of digital signalcircuitry 109 in the form of mechanical make/break key contacts 125 and123 that are coupled to respective separate key switch pins 120 and 122to provide an on/off digital output signal 111 when depressable keycomponent 101 is depressed to cause contacts 125 and 123 to make contactwith each other as shown in FIG. 2, i.e., by bending contact 123 towardcontact 125. In this regard, plunger body 114 also is provided as shownwith a positioning ridge 110 that is configured and positioned todisplace contact 123 toward contact 125 as depressable key component 101moves downward within key switch chassis housing 104. Positioning ridge110 may also be provided with a stepped and ramped surface 112 that isconfigured to mechanically interact or interfere with a bendable contactleg 126 that is biased against ramped surface 112 so as cause a “snap”or “click” action that is detectable by the user when depressable keycomponent 101 is depressed downward by a predetermined extent as shownin FIG. 2A.

In one embodiment where depressable key component 101 has a totaldownward travel length of about 4 millimeters, make/break key contacts125 and 123 may be configured such that the “make” (on or closedcondition) connection for the switch assembly 100 is made at about the 2millimeter downward travel position (i.e., greater than or equal toabout 50% downward travel) of depressable key component 101, while the“break” (off or open condition) connection for the switch assembly 100is maintained above the 2 millimeter downward travel position (i.e.,less than about 50% downward travel) of depressable key component 101.However, it will be understood that downward travel lengths that aregreater or less than about 4 millimeters may be employed as desired orneeded for a given application, and/or that make/break points may beconfigured to occur at positions of depressable key component 101 thatare greater than or less than 50% downward travel. For example, a totaldownward travel length of about 2 millimeters or 1.5 millimeters may beemployed in one embodiment for spring loaded mechanical key switchassemblies that are installed in a notebook computer or other relativelythin form factor information handling system. In such a case, the “make”connection for the switch assembly may be made at about the 1 millimeteror 0.75 millimeter downward travel position, respectively.

As further shown in FIG. 2A, displacement-sensing key well 150 includesvariable displacement-sensing circuitry 152 that in this exemplaryembodiment employs capacitive sensing technology to determine the travelposition of the plunger axle 108. In particular, variabledisplacement-sensing circuitry 152 of this embodiment includes a set ofelectrical sensors configured as a set of multiple stationary conductive(e.g., metal) elements in the form of aligned conductive sensor rings154 a to 154 d, and a movable conductive (e.g., metal) element 140(e.g., plate, ring, strip, etc.) that may be provided as shown disposedon a distal end of plunger axle 108 so that it travels with plunger axle108 to extend through successive conductive sensor rings 154 a to 154 din different positions as depressable key component 101 is depresseddownward. In FIGS. 2A-2B, conductive sensor rings 154 are drawn inperspective view for purpose of illustration relative to plunger axle108 which extends therethrough. Although illustrated as conductive ringsin FIG. 2A, it will be understood that stationary conductive sensor ring154 may be configured any other suitable geometry (bar-shaped solid,plate-shaped solid, rectangular or square ring shape, diamond ringshape, oval ring shape, etc.) for acting as a stationary capacitiveplate to allow measurement of the positioning of movable conductiveelement 140 relative to each of stationary conductive sensor rings 154in a manner as described elsewhere herein. The movable conductiveelement 140 may be made with a flat or non-flat surface relative to theconductive sensor rings 154. In one exemplary embodiment, the design andconfiguration of sensor rings 154 and movable conductive element 140 maybe made to ensure that the distance between the stationary and movableelements is constant and with a constant dielectric gap width betweenthe stationary and movable elements (in this case, air is thedielectric, although a dielectric is not limited to this and otherdielectric materials may be employed).

In the illustrated embodiment, movable conductive element 140, otherwiseknown as “the target”, functions as a movable capacitive plate which mayeither be coupled to ground or to any constant voltage, e.g., via wireconductor 170 or any other suitable method such as using an electricalconductor within metal plunger axle 108 that itself is electricallycoupled to ground or any constant voltage. Each of stationary conductiveelements 154 a to 154 d may function as individual stationary secondcapacitor plates that are each coupled to a respective analog signaltrace 160 as an input to displacement measurement circuitry 302 which inthis embodiment is provided in the form of a microcontroller (e.g., aTexas Instruments MSP430F55xx family of USB enabled 16-bit ultra-lowpower microcontrollers (MCU) (such as the MSP430F2111 or MSP430F5508),available from Texas Instruments of Dallas, Tex.) that runs firmwarestored on a memory device associated with the microcontroller. In thisembodiment, a voltage may be applied to the set of stationary conductivesensor rings 154, and changes in the electric field between each sensorring 154 and the movable target 140 are measured as values or relativelevels of induced voltage measured at each sensor ring 154. The peakvoltage of all the sensor rings 154 is sensed by thedisplacement-sensing circuitry 152 and used to determine the travelposition of the plunger axle 108, and thus the downward displacement ofdepressable key component 101. It will be understood however that anyother type of digital and/or analog displacement measurement circuitry302 may be employed that is suitable for measuring or otherwiserecognizing or reacting to changes in state of variable displacementsignals 160 of any variable displacement-sensing mechanical key switchassembly disclosed herein due to downward and upward travel ofdepressable key switch component 101 along the axis of plunger axle 108.

In one embodiment, displacement measurement circuitry 302 may employ RCcapacitive measurement methodology with falling edge event driveninterrupt performed on a per pin or signal trace basis. Furtherinformation on variable capacitive sensing and/or RC capacitivemeasurement may be found, for example, in U.S. patent application Ser.No. 12/316,703 filed Dec. 16, 2008; U.S. patent application Ser. No.12/802,468 filed Jun. 8, 2010; in U.S. patent application Ser. No.12/930,125 filed Dec. 29, 2010; and in U.S. patent application Ser. No.13/232,707 filed Sep. 14, 2011, each of which is incorporated herein byreference in its entirety. It will also be understood that any othertype of suitable capacitive-sensing circuitry may be employed including,for example, any circuitry that uses RC discharge time to measure sensorcapacitance as described in U.S. Pat. No. 3,936,674, which isincorporated herein by reference in its entirety.

In one exemplary embodiment, displacement measurement circuitry 302 maybe configured to monitor induced voltage on each of stationaryconductive elements 154 in real time via respective signal traces 160,including at any time during keyboard operation that depressable keycomponent 101 is depressed downward within key switch housing chassis104. In this regard, measured induced voltage will be greatest for anygiven one of stationary conductive elements 154 a to 154 d when movableconductive element 140 is positioned opposite (at its closest point to)the given stationary conductive element 154. Moreover, the relativeinduced voltage of stationary conductive elements 154 a to 154 d may becompared or otherwise analyzed to determine (e.g., by interpolation ofthe measured voltage values) a position of movable conductive element140 when it is located between any given two of stationary conductiveelements 154 a to 154 d, as well as when it is positioned aboveconductive element 154 a or below conductive element 154 d. For example,in a case where measured induced voltage is near baseline voltage(non-depressed value) for conductive elements 154 a and 154 b, while atthe same time measured induced voltage is at an elevated andsubstantially equal value for conductive elements 154 c and 154 d, aninterpolation may be made by displacement measurement circuitry 302 tocalculate the current position of movable conductive element 140 asbeing located in-between conductive elements 154 c and 154 d. Thisindicates that depressable key component 101 is almost entirely presseddownward to its furthest extent.

Thus, for example, in one exemplary embodiment, spring loaded mechanicalkey switch assembly 100 may be configured such that depressable keycomponent 101 has a total downward travel length of about 4 millimeterswithin cavity 121, although greater or lesser travel lengths arealternatively possible. In such an embodiment, four individualstationary conductive elements 154 may be spaced center-to-center byabout 0.5 millimeters apart, and such that the center of movableconductive element 140 is: directly opposite (or even with) the centerof stationary conductive element 154 a when depressable key component101 has been displaced downward by about 2 millimeters, directlyopposite (or even with) the center of stationary conductive element 154b when depressable key component 101 has been displaced downward byabout 2.5 millimeters (as shown in FIG. 2B), directly opposite (or evenwith) the center of stationary conductive element 154 c when depressablekey component 101 has been displaced downward by about 3 millimeters,and directly opposite (or even with) the center of stationary conductiveelement 154 d when depressable key component 101 has been displaceddownward by the full 4 millimeters displacement. Although fourstationary conductive elements 154 are illustrated in FIGS. 2A and 2B,it will be understood that any number of one or more stationaryconductive elements 154 may alternatively be employed depending on thedisplacement measurement resolution that is desired or needed for agiven application, including greater than or less than four stationaryconductive elements 154. Moreover, the center-to-center spacing betweenadjacent stationary conductive elements 154 may be selected to definethe desired granularity of key travel measurement to be detected fordepressable key component 101.

It will be understood that the embodiment of FIGS. 2A and 2B isexemplary only, and that other mechanical and electrical contactconfigurations of spring loaded mechanical key switch assembly 100and/or sensor configurations of displacement-sensing circuitry 152 maybe employed in other embodiments. In this regard, displacement-sensingcircuitry 152 may be any other suitable type, or combination of types,of sensor circuitry that is suitable for detecting changes in downwardtravel distance of plunger axle 108 corresponding to press depth of akey cap 102. For example, FIG. 3 illustrates another exemplaryembodiment of a spring loaded mechanical key switch assembly 300 that isalso configured to have variable displacement sensing capability usingoptical sensing circuitry. In this embodiment, key switch assembly 300also includes a depressable key component 101 that is movably receivedwithin a complementary dimensioned cavity 121 defined within key switchchassis housing 104. The depressable key component 101 may include a keycap 102 coupled to a shaft 103, plunger body 114, and plunger axle 108as shown.

Similar to the embodiment of FIGS. 2A and 2B, key switch housing 104 ofthe FIG. 3 embodiment includes a displacement-sensing key well 150having a plunger cavity 153 defined therein into which plunger axle 108is received when key cap 102 is depressed downward by a force 190 asshown in FIG. 4. An internal coil spring 106 (e.g., resting on the topof key well 150) may also be provided as before around plunger axle 108and configured to be compressed when key cap 102 is depressed downwardwithin key switch housing chassis 104. In FIG. 3, mechanical make/breakkey contacts 323 and 325 of one exemplary embodiment of digital signalcircuitry 109 are coupled to respective separate key switch conductors120 and 122 to provide an on/off digital output signal 111 whendepressable key component 101 is depressed to cause contacts 325 and 323to make contact with each other as shown in FIG. 4, i.e., in thisembodiment by bending contact 323 toward contact 325. After contact ismade, the 323 to 325 electrical make connection is continued thru theduration of the 2 mm-4 mm key travel (or other travel distance withwhich the key switch assembly has been configured). In this embodiment,plunger body 114 is provided with an extending finger 301 that ispositioned and configured to displace contact 325 toward contact 323 asdepressable key component 101 moves downward within key switch chassishousing 104. In this embodiment, no optional stepped and ramped surfaceis provided, so that no “snap” or “click” action is detectable by theuser when depressable key component 101 is depressed downward in themanner as of the embodiment of FIGS. 2A and 2B. Thus, it will beunderstood that variable displacement sensing capability may be providedfor a variety of configurations of spring loaded mechanical keyswitches, including different types of make/break contacts and/ordifferent configurations of depressable key components and key switchhousing chassis 104.

In the embodiment of FIGS. 3-4, a displacement-sensing key well 150 isemployed that includes displacement-sensing circuitry 152 that in thisexemplary embodiment includes multiple single channel optical sensorpairs configured as four multiple light sources (e.g., light emittingdiodes “LEDs” or other suitable light emitting elements) 350 a to 350 dstacked on top of each other on one side of plunger cavity 153 and thatare each mechanically and optically aligned with a corresponding one offour respective optical sensors (e.g., phototransistors) 352 a to 352 don the other side of the plunger cavity 153. Optical sensors 352 may be,for example, photo microsensors, or other suitable optical sensorelements) that are stacked on top of each other on an opposing side ofplunger cavity 153 as shown with each light source/optical sensor pairbeing positioned at a different key travel depth, it being understoodthat more than four or less than four optical sensor pairs may bealternatively employed depending on the displacement travel measurementresolution that is desired or needed for a given application. Moreover,a fewer number of light sources 350 may be provided than optical sensors352, e.g., one light source 350 configured to illuminate four opticalsensors 352.

One example of a suitable LED/phototransistor combination 350/352 knownas a Dual Channel Transmissive optical sensor is available as partnumber TCUT1300X01 from Vishay, and provides one LED paired to twophototransistors. Such a multi-channel optical sensor may be employed inone embodiment to achieve space savings over use of multiple singlechannel sensors. Examples of other suitable optical sensors includephototransistor devices available from Omron Electronic Components, LLC.In yet another embodiment, a displacement-sensing key well 150 may beemployed that includes displacement-sensing circuitry 152 that includesmultiple transmissive type photointerrupters such as ROHM part numberRPI-121 available from Rohm Co. Ltd. which are stacked on top of eachother (4 total shown). The transmissive type photointerrupter has a LEDlight source 350 on one side of plunger cavity 153 and is mechanicallyand optically aligned with a corresponding one of four respectiveoptical sensors (e.g., phototransistors) on the other side of theplunger cavity 153. Use of the transmissive type photointerrupter may beselected due to its ability to be minimally influenced from stray light.In yet another exemplary embodiment, a displacement-sensing key well 150may be employed that includes displacement-sensing circuitry 152 thatincludes multiple reflective type photo sensors such as ROHM part numberRPR-220 available from Rohm Co. Ltd.

As with the embodiment of FIGS. 2A-2B, depressable key component 101 maybe configured in one exemplary embodiment to have a total downwardtravel length capability of about 4 millimeters within cavity 121, andoptical sensor pairs may be spaced center-to-center by about 0.5millimeters apart, although other values of key component travel lengthand/or center-to-center spacing may be employed in other embodiments. Inthis regard, the center-to-center spacing between adjacent stackedoptical sensor pairs may be selected to define the desired granularityof key travel to be detected for a given depressable key component 101.In this embodiment, the number of displacement levels detected andreported by signals 160 corresponds to the number of optical sensorpairs provided within displacement measurement circuitry 302.

In operation of circuitry 152, each light source 350 is configured toemit a light beam across plunger cavity 153 to a corresponding one oflight sensors 352. As shown in FIG. 3, when depressable key component101 is in its non-depressed (fully-extended) state, plunger cavity 153is open to allow a light beam from each of light sources 350 to bereceived by its corresponding optical sensor 352, indicating thatdepressable key component 101 is not depressed. However, as shown inFIG. 4, as key cap 102 is depressed downward by a force 190, the distalend of plunger axle 108 enters plunger cavity 153 between the successivepairs of aligned light sources 350 and optical sensors 352 in differentpositions as depressable key component 101 is depressed downward asshown.

In this alternative embodiment, displacement measurement circuitry 302may be configured to monitor in real time analog signal traces 160corresponding to each of the individual respective optical sensors 352 ato 352 d to detect when a light beam from a corresponding respectivepaired light source 350 is being received across cavity 153, and when ithas been obscured by presence of plunger axle 108 within cavity 153. Inthis way, displacement measurement circuitry 302 may continuallydetermine and re-determine how far plunger axle 108 and depressable keycomponent 101 has been depressed or displaced downward at any given timebased on the which optical sensors 352 are still receiving light fromlight source/s 350. For example, in FIG. 4 the light sources 350 for alloptical sensors 352 have been blocked by plunger axle 108 except for thelowermost pair of light source 350 d/optical sensor 352 d. This state isindicated by signal traces 160 and may be communicated to displacementmeasurement circuitry 302, indicating to displacement measurementcircuitry 302 that depressable key component 101 has been depresseddownward to a distance that corresponds to location of optical sensor352 c (since optical sensors 352 a, 352 b and 352 c are blocked fromreceiving light from respective light sources 350 a, 350 b and 350 c)but not to a distance that corresponds to optical sensor 352 d (sincelight sensor 352 d still receives light from light source 350 d).

Still referring to the embodiment of FIGS. 3-4, spring loaded mechanicalkey switch assembly 300 is shown mounted (e.g., by “pop-in” mechanicalinterference fit) within an optional opening or hole 394 defined in acomponent side of a printed circuit board (PCB) 380 that includescircuitry, such as separate key switch conductors 120 and 122 that areconfigured for coupling to provide an on/off digital output signal 111(e.g., to circuitry such as a legacy keyboard controller 910 of FIG. 9),it being understood that a key switch assembly may be mounted to a PCB380 or other suitable support structure in any suitable manner, e.g.,including surface mounted to PCB 380. It will also be understood thatthe spring loaded mechanical switch assembly 100 of FIGS. 2A-2B may besimilarly mounted to a PCB, e.g., for a computer keyboard assemblyapplication. Any suitable type of displacement measurement circuitry maybe coupled to receive a signal output 160 of each of phototransistors352 via leads 326 extending from key switch chassis housing 104, e.g.,via signal traces that may be provided on PCB 380 as shown and solderedto leads 326 to provide signals from LED/phototransistor pairs (e.g.,such as to displacement measurement circuitry 302 of FIGS. 1-2 and 9).Power for light sources (LEDs) 350 may be provided by voltage signalsfound on the PCB 380 (e.g., a voltage trace on PCB 380, such as afiltered or switched version of a USB Vcc signal). In the particularembodiment of FIGS. 3-4, some of the sensors are found internal to thekey switch housing (on the component side of the PCB), and some arefound in the key switch housing but requiring a hole in the PCB toaccommodate deeper key travel distance.

In one exemplary embodiment, FIGS. 3-4 may be implemented usingdisplacement measurement circuitry 302 that is similar as the embodimentof FIGS. 1-2. For example, displacement measurement circuitry 302 may beprovided in the form of a controller, e.g., a 16-bit ultra-low powercapacitive sensing microcontroller part number MSP430F2111 availablefrom Texas Instruments of Dallas Tex. However, in this optical sensorembodiment, displacement measurement circuitry 302 may be configured tomeasure the voltage from each phototransistor output 160, and determinethe amount of key displacement.

FIGS. 3-4 also illustrate how optional key cap lighting may be providedfor spring loaded mechanical key switch assembly 300, it beingunderstood that similar key lighting components may be provided forother embodiments and different configurations of spring loadedmechanical key switch assemblies, such as those illustrated in FIGS. 1-2and FIG. 5. In this embodiment, key cap 102 (e.g., such as a plastic keycap) may have one or more light-transmissive key feature/s 302 (e.g.,such as a laser etched alphanumeric character, laser etched key cap rim,defined aperture, transparent or translucent key surface, and/or otherlight transmissive feature) that extends through the keycap 102 frombeneath the key cap 102 through the top surface of the key cap 102 suchthat light 398 emitted from beneath the key cap 102 by a light pipe 390is visible by a user from above the key cap 102 through the lighttransmissive key feature/s 302. One example of a top view of suchlight-transmissive key features 302 is illustrated in the embodiment ofFIG. 7. Further information on laser etched indicia and key rims may befound in U.S. Pat. No. 8,411,029, which is incorporated herein byreference in its entirety.

As shown in FIGS. 3-4, light pipe 390 passes through an opening 391defined in the key switch chassis housing 104 to one side of themechanical switch components (shaft 103, plunger body 114, plunger axle108, spring 106 and key well 150) from a planar light spreader component382 (e.g., acrylic sheet, polycarbonate sheet such as Lexan®, or othersuitable light-transmitting material) through an opening 392 defined inPCB 380 to a position beneath the key cap 102. Light pipe 390 may be anysuitable light conductive structure that is configured to pipe lightfrom light spreader 382 through PCB 380 and switch chassis housing 104to the underside of key cap 102. In one embodiment, light spreader 382may be a substantially light-transparent material that may be optionallylaser-etched to control diffusion of light received from light sources510, e.g., so as to control light spreading in order to contain emittedlight from selected light sources 510 within specified regions of lightspreader 382 such as further described in relation to FIG. 8.

As further shown in FIGS. 3-4, an optional light reflective film 384(e.g., flexible white colored plastic film) may be provided beneathlight spreader component 382 as shown for purposes of reflecting andspreading light from light sources 510 more evenly across light spreader382. In FIGS. 3-4, the space shown between PCB 380 and light spreader382, and the space shown between light spreader 382 and reflective film384 may be configured as suitable to allow for operative cooperationbetween these components, and in one exemplary embodiment these may beplanar components that are closely butted up against each other withsubstantially no space between the components with the exception thattolerance of spacing between PCB 380 and light spreader 382 may beconfigured to accommodate the depth of key well 150. Any needed ordesired spacing between PCB 380 and light spreader 382 may be providedby a separate spacer layer/s provided between PCB 380 and light spreader382, and length (and therefore depth) of light pipe 390 may be adjustedaccordingly to maintain suitable operative relationship with lightspreader 382.

Light pipe 390 of FIGS. 3-4 may be constructed of any suitable lighttransmissive material (e.g., such as acrylic, polycarbonate, etc.) andmay be configured as an elongated cylindrical shape as shown, althoughother shapes are possible such as elongated square shape, elongated ovalshape, elongated rectangular shape, etc. Light pipe 390 may be of anydimension (length, cross-sectional area, etc.) that is suitable fortransmitting sufficient light from light spreader 382 that is positionedbelow the key assembly 300 to illuminate a desired portion or portionsof key cap 102 in un-pressed or fully depressed position of the key cap102. The upper light-emitting end of light pipe 390 underneath key cap102 may be flush with a top surface of key switch chassis housing 104,or may alternatively be recessed below key switch chassis housing 104 orextend above key switch chassis housing 104. The upper light-emittingend of light pipe 390 underneath key cap 102 may also be optionallytextured, angled, or otherwise configured in a manner that diffusesemitted light 398 or directs the emitted light 398 in one or moredesired directions, e.g., such as directed toward the center of the keycap 102 and away from the outer edge of the key cap 102. Moreover, itwill also be understood that more than one light pipe 390 may beprovided to illuminate a key cap 102 of a given single spring loadedmechanical key switch assembly 300.

Still referring to FIGS. 3-4, a lower first end of light pipe 390 may bepositioned to butt up against or otherwise contact or lie adjacent tolight spreader component 382 in a manner that allows light to betransferred from light spreader 382 to light pipe 390. A relativelysmall diffuser area (e.g., a laser etched “dot”) may be provided onspreader 382 at each point where a given light pipe 390 contacts or liesadjacent light spreader 382 to facilitate transmission of light fromlight spreader 382 to the given light pipe 390. Light spreader 382 mayin turn be edge-lit from right-angle oriented LEDs (e.g., RGB LEDs orsingle color LEDs) 510 as shown, it being understood that light sources510 may be alternatively oriented relative to spreader 382 at anglesother than 90 degrees and/or in any other position relative to edges orsides of light spreader 382 that is suitable for emitting light that istransferred into light spreader 382. The light transferred from lightspreader 382 to light pipe 390 is then transmitted through light pipe390 so as to shine upwards to the underside of key cap 102 in a mannersuch that the light illuminates the light transmissive key feature 302in a manner that is visible by a user.

In the practice of the disclosed systems and methods, light pipe 390 maybe assembled to other components in any suitable manner. For example, inone exemplary embodiment, light pipe 390 may be pre-assembled as anintegral part of a spring loaded mechanical key switch assembly 300 thatis then assembled to PCB 380 through aperture 392 at the same time theremainder of spring loaded mechanical key switch assembly 300 (e.g., keywell 150 and electrical pins 323, 325 and 326) are assembled to PCB 380.In another exemplary embodiment, light pipe 390 may be provided as anintegral part of light spreader 382 (e.g., glued to or inserted with afriction fit into an complementary-dimensioned opening defined in theupper surface of spreader 382) to which the spring loaded mechanical keyswitch assembly 300 and PCB 380 are then assembled by sliding aperture392 of the key switch housing chassis 104 over light pipe 390 whenassembling key assembly 300 to PCB 380.

FIG. 5 illustrates another exemplary embodiment of a lighted springloaded mechanical key switch assembly 500 having a key cap 102 withlight transmissive key feature 302 but that does not have havingvariable displacement sensing capability. In this regard, spring loadedmechanical key switch assembly 500 is provided with plunger cavity 553defined within a key well 550 that includes no displacement sensingcircuitry but that otherwise has digital make/break mechanical keycontact circuitry similar to the embodiment of FIGS. 2A-2B. As shown,spring loaded mechanical key switch assembly 500 includes a light pipe390 that is similarly configured to illuminate light transmissive keyfeatures 302 from light provided by light spreader 382 in the manner ofthe embodiment of FIGS. 3 and 4. Although not illustrated, lightedspring loaded mechanical key switch assembly 500 may also be providedwith any suitable digital signal circuitry 109 such as describedelsewhere herein. In yet another embodiment, a lighted spring loadedmechanical key switch assembly having a plunger cavity 153 definedwithin a displacement-sensing key well 150 that includes variabledisplacement-sensing circuitry 152, but that has no digital make/breakmechanical key contact circuitry or other type of digital signalcircuitry 109, may be provided with a light conductive structure such asa light pipe 390, e.g., to illuminate light transmissive key features302 of a keycap 102 of a key switch assembly that is incapable ofproviding on/off digital output signals 111.

FIG. 6 illustrates a side view of a keyboard assembly 600 that includesmultiple spring loaded mechanical key switch assemblies 300 that areassembled to PCB 380, light spreader 382, and reflective film 384 in amanner as previously described. As shown, multiple edge mounted rightangle light sources 510 are arrayed around at least two edges of lightspreader 382 to provide light for illuminating spreader 382, light pipes390 and key caps 102 of keyboard assembly 600. Further shown is anoptional face plate 610 (e.g., planar sheet of metal and/or plastic)that may be provided to shield the light spreader from user view,provide ruggedness and mechanical support to the key housing 104 and toprotect the internal components of the keyboard assembly 600. Each offace plate 610, PCB 380, light spreader 382, and reflective film 384 maybe operatively supported in relation to each other from edge mountingpoints (e.g., brackets, grooves, shelves, etc.) provided on the interiorsides or other surfaces of a chassis 691 that surrounds or otherwisehouses the components of keyboard assembly 600.

FIG. 7 illustrates an exploded perspective view of a keyboard assembly700, showing positioning of four spring loaded mechanical key switchassemblies 300 with plastic mounting guides 395 that are each positionedfor assembly into key assembly openings 394 defined in PCB 380. Alsoshown are light pipes 390 corresponding to each key switch assembly 300that are positioned for insertion into four corresponding light pipeopenings 392 defined in PCB 380. Light spreader 382 is shown positionedbetween PCB 380 and a combination flex circuit assembly 620 thatincludes reflective film 384 integrated together with right anglemounted light sources 510 onto a flex circuit component (e.g.,polyimide, polyether (ether) ketone, transparent conductive polyester,etc.). In this regard, light sources 510 may be adhered or otherwisemounted to the flex circuit sheet before assembly to light spreader 382and PCB 380 as part of a keyboard assembly that is contained within orotherwise mounted as part of a keyboard chassis, e.g., with an optionalface plate 610 overlying PCB 380 as shown in FIG. 6. In one exemplaryembodiment, a flex circuit may be adhered to the underside of a thinwhite reflective plastic-like film 384, and the flex circuit may beconfigured to route, for example, the LED power and return signals,current limiting resistors, and right angle surface mount RGB LEDs. Acutout may be provided in the reflective film 384 to allow each rightangle LED to pop up thru the top side of the reflective film 384 so thatthe LED can light up the cross-sectional area (or side) of the lightspreader 382.

Also shown in FIG. 7 are four additional pairs of key assembly openings394 and light pipe openings 392 defined in PCB 380 for receivingadditional spring loaded mechanical key switch assemblies 300 and lightpipes 390. In this regard, it will be understood that a keyboardassembly may be configured with any pattern and number of pairs of keyassembly openings 394 and light pipe openings 392 as needed or desiredto fit a given back-lighted keyboard application. For example, in oneexemplary embodiment, 104 pairs of key assembly openings 394 and lightpipe openings 392 may be defined in PCB 380 in a pattern suitable formounting and backlighting 104 spring loaded mechanical key switchassemblies 300 of a QWERTY keyboard, although other patterns and numbersof pairs of key assembly openings 394 and light pipe openings 392 may beprovided in other embodiments to support other types and sizes ofkeyboard assemblies.

FIG. 8 illustrates a top view of one exemplary embodiment of a singlesheet light spreader component 382 assembled to right angle mountedlight sources 510 in an operative relationship to provide multipleseparate backlighting zones (zones 1, 2, 3 and 4 labeled as 802, 804,806 and 808) for a keyboard assembly. In such an embodiment, eight lightsources 510 may be mounted onto a combination flex circuit assembly 620that underlies light spreader 382 and is not visible in FIG. 8. In oneembodiment, such a light spreader configuration may be provided for afull size computer keyboard assembly, such as a 104-key QWERTY keyboardassembly. In such an embodiment, each backlighting zone may bedimensioned and configured to underlie and separately light a portion ofthe total number of keys. Distance between the LEDs 510 of adjacentzones, and/or the angle at which each LED 510 emits light into the lightspreader 382 may be selected to minimize light bleeding between adjacentzones. Although FIG. 8 illustrates a single sheet light spreadercomponent 382, it will be understood that a light spreader component 382having multiple sheets or multiple light-transmissive segments is alsopossible. Further, it will be understood that in other embodiments notall key switch assemblies need be back-lighted, nor do all segments of akeyboard assembly need to underlain by a light-transmissive lightspreader component.

As an example, positions for multiple key assembly openings 394 andcorresponding light pipe openings of an overlying PCB 380 areillustrated in dashed outline to show how each backlighting zone 802,804, 806 and 808 of a light spreader 382 may separately illuminate adifferent group of spring loaded mechanical key switch assemblies 300.Specifically, FIG. 8 illustrates a configuration capable of backlighting15 mechanical key switch assemblies 300 in each of zones 1, 2 and 3; and21 mechanical key switch assemblies in zone 4, using two light sourcesin each zone. This translates into a ratio of backlit keys to lightsources that is equal to 66 keys/8 light sources or 8.25 backlit keysper light source. Thus, using the disclosed systems and methods, keycaps 102 of multiple spring loaded mechanical key switches may bebacklit by one or more common light sources 510 to achieve a ratio ofbacklit keys to light sources that is greater than 1. This is as opposedto conventional spring loaded mechanical key switches that each employ aseparate LED for key lighting, i.e., using a ratio of backlit keys tolight sources that is equal to 1.

Advantageously, the disclosed systems and methods thus may beimplemented in one embodiment using fewer light sources powered only byUSB bus power (without an AC adapter) to backlight substantially all thekeys of a large keyboard assembly (e.g., including keyboard assemblieshaving 80 or more keys such as a 104-key QWERTY keyboard) than would berequired by a conventional spring loaded mechanical key switch keyboardassembly of similar size and having one light source per key (whichwould require use of an AC adapter). For example, a typical RGB LEDlight source draws 60 milliamps (20 mA for red, 20 mA for green, and 20mA blue). Thus a conventional mechanical key switch keyboard assemblywith 104 keys that each has its own RGB LED key light would draw a total31 watts to power the 104 LEDs alone, and would therefore require anAC/DC adapter to power the lighted keyboard assembly. In contrast, a104-key mechanical key switch keyboard assembly employing 12 edgemounted RGB LEDs as light sources 510 to illuminate a light spreader 382and light pipes 390 provided for each key in a manner as disclosedherein would only draw a total of 3.5 watts, and could therefore bepowered by two USB 2.0 ports from an attached information handlingsystem, which have a maximum capacity of 5 watts. This avoids the needfor powering the disclosed keyboard assembly from an AC/DC adapter.

In an embodiment such as illustrated in FIG. 8, light sources 510 ₁ maybe separately controlled to provide different lighting characteristics(e.g., different light intensity, different light color, different lightflashing pattern, etc.) and/or lighting animation/graphics at any giventime to the light pipes and key caps overlying zone 1 than light sources510 ₂, 510 ₃ and 510 ₄ display to the light pipes and key caps overlyingzones 2, 3, and/or 4. Each of zoned light sources 510 ₂, 510 ₃ and 510 ₄may also be separately controlled relative to light sources 510 ₁ and toeach other. In this way, light sources 510 of the different zones 802,804, 806 and 808 may be individually controlled to display a lightpattern that moves across the keyboard area (e.g., such as a sequentialchange of color or flashing pattern in the form of a “wave” moving fromone zone to another across the keyboard), to display different colorssimultaneously in different zones, to display a pattern of flashinglight in one zone while all other zones are non-flashing, etc.

FIG. 9 illustrates a block diagram for a keyboard system 900 includingboth variable displacement-sensing spring loaded mechanical key switchassemblies 904 and digital output-only spring loaded mechanical keyswitch assemblies 906 (e.g., that do not have displacement-sensingcircuitry 152). Examples of conventional spring loaded mechanical keyswitch assemblies 906 include, but are not limited to, Cherry MX KeySwitches available from ZF Electronic Systems of Pleasant Prairie, Wis.;and Kailh Switches available from Kaihua Electronics Co., Ltd fromTangxia Town, Dongguan City, Guangdong Province, China. Each of variabledisplacement-sensing mechanical key switch assemblies 904 may be, forexample, a spring loaded mechanical key switch assembly 10, 100, or 300such as described herein in relation to FIGS. 1, 2A-2B, 3 and 4. Each ofmechanical key switch assemblies 906 may be, for example, a conventionalspring loaded mechanical key switch assembly or a key switch assemblythat is similar to one of spring loaded mechanical key switch assemblies10, 100, or 300 but without the displacement-sensing circuitry 152 andvariable displacement output signals 160. Key switch assemblies 904 and906 may together be provided in any suitable number or configuration,e.g., so as together implement a total of 104 mechanical key switchassemblies to implement a QWERTY keyboard configuration, with just aportion of the total keys (e.g., corresponding to W, A, S and D keys)being variable displacement-sensing spring loaded mechanical key switchassemblies 904. It will be understood, however, that all key switchassemblies of a keyboard may alternatively be configured as variabledisplacement-sensing spring loaded mechanical key switch assemblies 904.

Also illustrated in FIG. 9 are optional backlighting circuitrycomponents, that include one or more backlight controller/s 920, e.g.,such as an ST Micro 8051F347 microcontroller available from STMicroelectronics of Geneva, Switzerland. In such an embodiment, eventdriven backlighting may be implemented by communicating events from anapplication programming interface (API) executing on a host informationhandling system across communication interface 907 to the backlightcontroller 920, which responds by communicating lighting commands (e.g.,via I²C bus) to light source current driver circuitry component/s 931which each drive one or more light sources (e.g. LEDs) 510 accordinglyto control on, off and/or color operation of the light sources. In oneexemplary embodiment, each of light source current driver circuitrycomponent/s 510 may be a MAX7313 serial interfaced peripheral availablefrom Maxim Integrated of San Jose, Calif., each of which is capable ofdriving up to five RGB LEDs 510 of a given backlighting zone 802, 804,806 or 808 of light spreader 382 of FIG. 8, e.g., to light individualspring-loaded mechanical key switch assemblies 300 or 500 equipped withlight pipes 310 previously described.

As depicted in FIG. 9, for this embodiment a keyboard controller 910 iscoupled to receive an on/off digital output signal 111 (e.g., via alegacy key matrix) from digital signal circuitry 109 of each key switchassembly 904 and 906 that is detected by controller 910 as representinga digital key switch assembly that is either pressed or not pressed.Keyboard controller 910 may be implemented, for example, as amicrocontroller (e.g., legacy 8051-based microcontroller or custommicrocontroller) that runs firmware stored on a memory device associatedwith the keyboard controller 910. Control circuitry within the keyboardcontroller 910 processes these digital key signals 111 and is connectedto an output communication path so that this processed digital keyinformation 950 can be communicated to external devices that areexternal to the keyboard system 900, such as host components of aninformation handling system (e.g., such as desktop computer or notebookcomputer) that includes a host processor such as a CPU, e.g., through auniversal serial bus (USB) interface 907 or other suitable interface. Inone exemplary embodiment, all components of keyboard system 900 maycontained within a chassis 691 of a keyboard assembly 600 such asillustrated in FIG. 6, although this is optional. In such a case,external devices such as host processing devices, may be coupled toreceive signals from the components of keyboard system 900 that arecontained within a chassis 691.

In addition, external devices can optionally communicate control and/orother configuration information to the keyboard controller through thissame output communication interface 950. Further information on legacykeyboard controller operation may be found in U.S. patent applicationSer. No. 12/802,468 filed Jun. 8, 2010; in U.S. patent application Ser.No. 12/930,125 filed Dec. 29, 2010; and in U.S. patent application Ser.No. 13/232,707 filed Sep. 14, 2011, each of which is incorporated hereinby reference in its entirety. Examples of possible information handlingsystem components may be found described in U.S. patent application Ser.No. 12/586,676, filed Sep. 25, 2009, now U.S. Pat. No. 8,307,222; and inU.S. patent application Ser. No. 13/232,707 filed Sep. 14, 2011, each ofwhich is incorporated herein by reference in its entirety.

Still referring to FIG. 9, displacement-sensing circuitry 152 of eachkey switch assembly 904 provides variable displacement signals 160 todisplacement measurement circuitry 302 as shown. For example, in theexemplary embodiment of FIGS. 3-4, multiple phototransistor outputs 160may be routed to GPIO input lines of a microcontroller configured tooperate as displacement measurement circuitry 302. Variable displacementsignals 160 may be analog signals indicating the amount of downwarddisplacement that has been applied to depressable key components 101 ofone or more key switch assemblies 904, as previously described. When agiven spring loaded mechanical switch assembly 904 is depressed, one ormore corresponding analog signal/s 160 indicating or indicative of theamount of downward displacement that has been applied to depressable keycomponents 101 of the given key switch assembly 904 may be provided tovariable displacement analysis block 990 displacement measurementcircuitry 302 as shown. It will be understood that in one embodiment thevariable displacement signals 160 may alternatively be multiplexed witheach other to reduce the number of separate signal paths 160 required,e.g., using a crossbar switch or other suitable signal multiplexingtechnology. In another exemplary embodiment, multiple variabledisplacement keys 904 may be pressed simultaneously, and multiplecorresponding analog signal outputs 160 received from each key 904 maybe processed by the displacement measurement circuitry 302 for each ofthe multiple displacement outputs 951 reported (one per respective key904).

Following is an exemplary description of the operation for a dualmake/break and displacement sensing operation of a spring loadedmechanical key switch assembly 300 such as illustrated in FIGS. 3-4,assuming for sake of illustration only that the spring loaded mechanicalkey switch assembly 300 is configured to support a total of 4 millimeterof downward travel for depressable key component 101 from fully extendedposition and has four optical sensor pairs 350/352. In this example, theoperation of spring loaded mechanical key switch assembly 300 proceedsas follows in response to a downward pressure 190 applied by the fingerof a user.

First, as the user presses the keycap 102 and depressable key component101 downward by about 2 millimeters (i.e., about 50% of full traveldistance), the electrical “make” connection is made by virtue of contactbetween make and break key contacts 325 and 323 and is reported to thekeyboard controller 910 (e.g., a conventional legacy Keyboard MCU). Inparallel and at the same time, the first (uppermost) optical sensor pair350 a/352 a detects that depressable key component 101 has traveleddownward to its depth and sends a corresponding signal 160 a to thedisplacement measurement circuitry 302 to indicate this has keydisplacement event occurred. As shown in FIGS. 3-4, other sensor pairs350/352 are stacked on top of one another, e.g., to detect eachadditional 0.5 mm travel of key press depth from one another. Thus, as auser continues to press keycap 102 and depressable key component 101further downward to about 2.5 millimeters, the second optical sensorpair 350 b/352 b detects this occurrence and sends a correspondingsignal 160 b to the displacement measurement circuitry 302 to indicatethis key displacement event has occurred. Similarly as a user continuesto press keycap 102 and depressable key component 101 further downwardto about 3 millimeters the third optical sensor pair 350 c/352 c detectsthis occurrence and sends a corresponding signal 160 c to thedisplacement measurement circuitry 302 to indicate this key displacementevent has occurred. Finally, as a user continues to press keycap 102 anddepressable key component 101 further downward to about 3.5 millimetersthe fourth optical sensor pair 350 d/352 d detects this occurrence andsends a corresponding signal 160 d to the displacement measurementcircuitry 302 to indicate this key displacement event has occurred.

Displacement measurement circuitry 302 may be provided in one exemplaryembodiment as an integrated part of a keyboard device body, e.g.,contained within a chassis of the keyboard together with othercomponents of a keyboard assembly such as illustrated in FIGS. 6 and 7.However, one or more components and/or processing tasks of displacementmeasurement circuitry 302 may alternatively be integrated or otherwiseimplemented within a microcontroller that is operating as the keyboardcontroller 910 and/or as part of the host information handling system towhich the keyboard is connected, if desired. One or more of thecomponents of displacement measurement circuitry 302 could also beimplemented with external circuitry, as well. Thus, it will beunderstood that the components and/or processing tasks of displacementmeasurement circuitry 302 may be implemented by any alternativeconfiguration of one or more processing devices (e.g., controller,microcontroller, processor, microprocessor, ASIC, FPGA, CPU, etc.) of aninformation handling system or a peripheral component thereof, and aloneor together with other types of information handling system processingtasks.

In the embodiment of FIG. 9, displacement measurement circuitry 302includes a variable displacement analysis block 990 (that receivesvariable displacement signals 160) and memory that include variabledisplacement profile data 995 (e.g., as user configurable controlparameters per level or extent of sensed key displacement on a per gameor per application basis). In this embodiment, the variable displacementprofile data may be loaded and/or modified in memory 995 from anexternal device across communication path 951, e.g., from an attachedhost using an application programming interface (API). The variabledisplacement profile data may be loaded from memory 995 into theVariable Displacement Analysis block (VDA) 990. The profile data 995 maybe used by VDA block 990 as parameters for making decisions in the VDAblock 990, e.g., such as understanding how much key switch displacementis required before triggering a particular scan code, and/or forspecifying behavior resulting from any particular pressed variabledisplacement-sensing spring loaded mechanical key switch assembly 904.The scan code is output from the VDA 990 via the communication path 951to the communication interface 907 to an external device (e.g., such asto a Host PC system via a USB bus interface).

In one exemplary embodiment, a user may assign a multi-charactersequence (or macro) to the variable displacement profile data 995 for atleast one given variable displacement-sensing key switch assembly 904that corresponds to one or more particular sensed displacement levelsfor the given key assembly 904. When it is sensed that the given keyassembly 904 is pressed and a given displacement level is sensed, aunique scan code 901 corresponding to the sensed displacement level maybe output from displacement measurement circuitry 302 and sent via path951 to an appropriate device driver (e.g., USB Human Interface Device“HID” driver) executing on a CPU of a host system. The USB HID devicedriver may then generate and send a HID keyboard report in the form of avariable displacement keyboard event to a variable displacement macroselector component of a middleware layer executing on the CPU of thehost system. The variable displacement macro selector componentintercepts this keyboard event information and may in turn provide amodified variable displacement scan code to a user application layerthat provides the multi-character sequence desired for the senseddisplacement level of the given key switch assembly 904. For example,keyboard profile data 995 may be customized on a per game basis, and theappropriate profile data 995 loaded into the VDA 990 once thecorresponding game is loaded and running on the connected hostinformation handling system.

In one exemplary embodiment, this capability may be supported byassigning individual macros to an unassigned scan code 901 that is oneof multiple scan codes 901 supported by each variabledisplacement-sensing key switch assembly 904 of a keyboard assembly orother input/output device. In this way, scan codes may be dynamicallyselected in real time depending on the amount of pressure translatinginto measured key displacement that is applied to a given key switch 904based on the user defined profile data 995 for that given key switch904, in a manner as described for variable pressure sensing in in U.S.patent application Ser. No. 12/930,125 filed Dec. 29, 2010; and in U.S.patent application Ser. No. 13/232,707 filed Sep. 14, 2011, each ofwhich is incorporated herein by reference in its entirety. In thisregard, variable displacement-based scan codes 901 may be generated andprocessed in the same manner as described for VPS scan codes in U.S.patent application Ser. No. 13/232,707, in which case the same type ofUSB HID driver may receive the variable displacement-based scan codes asreceives the VPS pressure-based scan codes in U.S. patent applicationSer. No. 13/232,707. Moreover, the variable displacement keyboard eventsmay be generated by the USB HID driver in the same manner as VPSkeyboard events are generated in U.S. patent application Ser. No.13/232,707, and the USB HID driver may provide these variabledisplacement keyboard events to a variable displacement macro selectorof a middleware layer that operates in the same manner as VPS macroselector component of U.S. patent application Ser. No. 13/232,707, andwhich in turn may select the modified variable displacement-based scancodes (e.g., macro information in the form of a multi-key sequence) froma variable displacement profile based on the identity of the pressed keyand the sensed displacement level of the pressed key in the same manneras VPS macro selector component of U.S. patent application Ser. No.13/232,707 performs these tasks based on identity of a pressed key andthe key's pressure level sensed.

Thus, a single spring loaded mechanical switch key assembly may beemployed to support performing, for example, 5 macros (acting as 5virtual keys), to support switching between macro outputs in real-timebased on a variable input such as sensed key displacement, and/or tosupport different (e.g., user programmable and/or selectable)correlations of key output behaviors to sensed key displacement. It willbe understood that use of scan codes and other variable pressure sensingfeatures described in U.S. patent application Ser. No. 12/930,125 filedDec. 29, 2010 and in U.S. patent application Ser. No. 13/232,707 withregard to pressure-sensing digital output circuitry andvariable-pressure keys may be similarly implemented using displacementmeasurement circuitry 302, e.g., using sensed key displacement as aproxy for sensed key pressure.

It will be understood that the particular embodiments illustrated hereinare exemplary only, and that the components and function of displacementmeasurement circuitry 302 may be implemented using any one or morecircuitry components suitable for receiving analog signals 160representative of key displacement from variable displacement-sensingcircuitry 152 of key switch assemblies 904, and for selecting andproviding in real time scan code/s corresponding to the key displacementapplied to each of key switch assemblies 904. In addition, externaldevices may optionally communicate control and/or other configurationinformation to the displacement measurement circuitry 302 and/orkeyboard controller 910 through communication interface 907. Although aUSB interface 907 is illustrated in FIG. 9, it will be understood thatcommunication paths 950 and/or 951 may alternatively communicate withother devices in other wired or wireless ways, for example, via aBluetooth interface if a wireless interface is desired.

Also illustrated in FIG. 9 is optional mode signal 961 that may beprovided from variable displacement analysis block 990 of displacementmeasurement circuitry 302 to keyboard controller 910 to indicate tokeyboard controller 910 whether or not to output processed digital keyinformation on output communication path 950 corresponding to on/offdigital output signals 111 from variable displacement-sensing key switchassemblies 904. For example, during a designated variable displacementoperation mode, one or more of key assemblies 904 may be designated forsole operation as variable displacement keys (e.g., such as W, A, S andD keys). In such a variable displacement-only operation mode, keyboardcontroller only outputs displacement-based scan codes 901 based onsignals 160 from key switch assemblies 904, but does not output digitalkey information 950 corresponding to on/off digital output signals 111received from key switch assemblies 904.

However, in some cases, the attached host information handling systemsmay enter a standby or a security state (e.g., due to a specifiedelapsed time of inactivity) that requires entry of a password usingdigital on/off key signals 111 entered from one or more of thedesignated “variable displacement only” key switch assemblies 904. Inother cases, a user may desire to use one or more of the designated“variable displacement only” key switch assemblies 904 as momentary ondigital keys to provide digital on/off key signals 111, e.g., for dataor password entry. Accordingly, displacement measurement circuitry 302may be controlled (e.g., by a control signal received from a hostprocessor on occurrence of host standby condition, and/or by userkeyboard entry code) to provide mode signal 961 to cause keyboardcontroller 910 to output processed digital key information 950corresponding to on/off digital output signals 111 received from keyswitch assemblies 904 for as long as necessary or desired, e.g., for aparticular operation purpose. In this way, mode signal 961 may be usedto toggle key operation for variable displacement-sensing key switchassemblies 904 between “variable displacement-only” analog outputoperation and digital output operation.

It will be understood that in further embodiments, displacementmeasurement circuitry 302 may alternatively or additionally beimplemented to process analog variable displacement signals 160 receivedfrom variable displacement-sensing key switch assemblies 904 in the samemanner that pressure-sensing digital output circuitry processes analogoutput signals from variable pressure sensing analog keys as describedin U.S. patent application Ser. No. 13/232,707 filed Sep. 14, 2011,which is incorporated herein by reference in its entirety. Further,keyboard controller 910 may alternatively or additionally be implementedto process on/off digital output signals 111 from digital signalcircuitry 109 of each key switch assembly 904 and 906 in the same mannerthat legacy keyboard controller 110 processes digital output signalsreceived via a key matrix from digital keys as described in U.S. patentapplication Ser. No. 13/232,707 filed Sep. 14, 2011, which isincorporated herein by reference in its entirety. In this way, variabledisplacement-sensing capability may be advantageously utilized toimplement variable pressure features, and operation of displacementmeasurement circuitry 302 may interact with operation of keyboardcontroller 910 in the same way that pressure-sensing digital outputcircuitry interacts with the legacy keyboard controller of U.S. patentapplication Ser. No. 13/232,707.

Further, it will also be understood that legacy keyboard support and/orhaptics capability may be provided to a keyboard assembly that employsvariable displacement sensing spring loaded mechanical key switchassemblies 904 by utilizing features similar to those described in U.S.patent application Ser. No. 12/930,125 filed Dec. 29, 2010, which isincorporated herein by reference in its entirety. In this regard,displacement measurement circuitry 302 may be configured to output toswitching circuitry a high and low (high/low) digital output bit streamsignal having a frequency that is representative of the degree orpercent of downward displacement being currently applied to adepressable key component 101 of one or more of variable pressuresensing mechanical key switch assemblies 904, and the switchingcircuitry may then provide a toggled key pressure indication signal inthe form of alternating open/short (off/on) digital signal to a legacykeyboard controller in a manner that emulates toggling of a conventionalmomentary off/on digital key. Additionally or displacement measurementcircuitry 302 may be configured to output to provided haptics controlcircuitry a digital signal (e.g., high/low digital signal)representative of the degree or percent of downward displacement beingcurrently applied to a depressable key component 101 of one or morevariable pressure sensing mechanical key switch assemblies 904, which inturn provides a haptics control signal to cause provided hapticsactuation circuitry of variable displacement sensing spring loadedmechanical key switch assemblies 904 to produce a variable hapticsmotion characteristic corresponding to the pressure level applied to thegiven pressure sensitive key (e.g., as a vibration waveform having aparticular vibration intensity and/or frequency that corresponds to thecurrently applied real time key pressure level). Examples of suchhaptics actuation circuitry include a piezo transducer that may beprovided within or under a keycap 102 as separate circuitry from thehaptics actuation circuitry of any other keycaps 102 of a keyboardassembly as described in U.S. patent application Ser. No. 12/930,118filed Dec. 29, 2010, which is incorporated herein by reference in itsentirety.

It will be understood that one or more of the tasks, functions, ormethodologies described herein may be implemented, for example, asfirmware or other computer program of instructions embodied in anon-transitory tangible computer readable medium that is executed by aCPU, controller, microcontroller, processor, microprocessor, FPGA, ASIC,or other suitable processing device.

For purposes of this disclosure, an information handling system mayinclude any instrumentality or aggregate of instrumentalities operableto compute, calculate, determine, classify, process, transmit, receive,retrieve, originate, switch, store, display, communicate, manifest,detect, record, reproduce, handle, or utilize any form of information,intelligence, or data for business, scientific, control, or otherpurposes. For example, an information handling system may be a personalcomputer (e.g., desktop or laptop), tablet computer, mobile device(e.g., personal digital assistant (PDA) or smart phone), server (e.g.,blade server or rack server), a network storage device, or any othersuitable device and may vary in size, shape, performance, functionality,and price. The information handling system may include random accessmemory (RAM), one or more processing resources such as a centralprocessing unit (CPU) or hardware or software control logic, ROM, and/orother types of nonvolatile memory. Additional components of theinformation handling system may include one or more disk drives, one ormore network ports for communicating with external devices as well asvarious input and output (I/O) devices, such as a keyboard, a mouse,touch screen and/or a video display. The information handling system mayalso include one or more buses operable to transmit communicationsbetween the various hardware components.

While the invention may be adaptable to various modifications andalternative forms, specific embodiments have been shown by way ofexample and described herein. However, it should be understood that theinvention is not intended to be limited to the particular formsdisclosed. Rather, the invention is to cover all modifications,equivalents, and alternatives falling within the spirit and scope of theinvention as defined by the appended claims. Moreover, the differentaspects of the disclosed systems and methods may be utilized in variouscombinations and/or independently. Thus the invention is not limited toonly those combinations shown herein, but rather may include othercombinations.

What is claimed is:
 1. A keyboard system, comprising: a light spreadercomponent comprised of light transmissive material; one or more lightsources positioned to direct light into the light transmissive materialof the light spreader component; at least one spring loaded mechanicalkey switch assembly comprising: a key switch chassis housing having afirst end and a second end, a depressable key component movably receivedwithin the key switch chassis housing and having a first end and asecond end, the first end of the depressable key component being movablebetween an extended position and a depressed position relative to thefirst end of the key switch chassis housing with the first end of thedepressable key component being closer to the first end of the keyswitch chassis housing in the depressed position than in the extendedposition, a spring element configured to provide a resilient force toresist downward movement of the depressable key component from theextended position to the depressed position, at least one of digitalsignal circuitry configured to provide an on/off digital output signalwhen the depressable key component is depressed downward by apredetermined extent, variable displacement-sensing circuitry configuredto detect displacement of the depressable key component relative to thekey switch chassis housing and to provide one or more variabledisplacement signals that vary in character based on the amount ofdisplacement of the depressable key component between the extendedposition and the depressed position, or a combination thereof, and atleast one light conductive structure having first and second ends andextending from the second end of the key switch chassis housing to thefirst end of the key switch chassis housing, the first end of the lightconductive structure being positioned adjacent the first end of the keyswitch chassis housing and the second end of the light conductivestructure being positioned adjacent the second end of the key switchchassis housing; where a second end of the light conductive structure ispositioned to receive light from the light spreader component; where thelight conductive structure is configured to conduct light received fromthe light spreader to the first end of the light conductive structure;and where the first end of the light conductive structure is configuredto emit the conducted light from the first end of the light conductivestructure.
 2. The system of claim 1, where the depressable key componentfurther comprises a keycap on the first end of the depressable keycomponent; where the light conductive structure comprises a light pipe;and where the keycap comprises a top surface and an underside surfaceopposite the top surface, the underside surface of the keycap facing thefirst end of the light conductive structure to receive the light emittedtherefrom, and the top surface of the keycap facing upward toward a userof the keyboard system; where the keycap further comprises one or morelight transmissive features extending through the keycap from theunderside surface to the top surface of the keycap such that lightemitted from beneath the key cap by the light conductive structure isvisible by a user of the keyboard system from above the key cap throughthe light transmissive key features.
 3. The system of claim 2, where thelight transmissive features comprise at least one of a laser etchedalphanumeric character, a laser etched key cap rim, an aperture definedin the keycap, a transparent or translucent keycap material, or acombination thereof.
 4. The system of claim 1, where the at least onespring loaded mechanical key switch assembly comprises multiple suchspring loaded mechanical key switch assemblies; where the light spreaderis a planar light spreader component; and where a second end of thelight conductive structure of each of the multiple spring loadedmechanical key switch assemblies is positioned to receive light from thesame planar light spreader component as is the second end of the lightconductive structure of each of the other multiple spring loadedmechanical key switch assemblies.
 5. The system of claim 1, where thelight spreader is a substantially planar light spreader component; andwhere the system further comprises: a substantially planar printedcircuit board (PCB) disposed between the first end of the key switchchassis housing and the light spreader component with a plane of the PCBbeing oriented in substantially parallel relationship with a plane ofthe light spreader component, and with a first opening being defined toextend through the PCB that is dimensionally configured to receive thelight conductive structure therein; and where the light conductivestructure extends from the key switch chassis housing through the firstopening defined in the PCB such that the second end of the lightconductive structure is positioned between the PCB and the lightspreader component in a position adjacent to the light spreadercomponent to receive the light from the light spreader component.
 6. Thesystem of claim 5, where a second opening is defined to extend throughthe PCB adjacent to the first opening; and where the key switch assemblyfurther comprises a mounting guide that is dimensionally configured tobe received within the second opening, the mounting guide beingassembled into the second opening to mount the key switch assembly tothe PCB with the light conductive structure extending from the keyswitch chassis housing through the first opening defined in the PCB. 7.The system of claim 6, where the at least one spring loaded mechanicalkey switch assembly comprises multiple such spring loaded mechanical keyswitch assemblies; where multiple adjacent first and second openingscorresponding to the multiple key switch assemblies are defined toextend through the PCB; and where each of the given multiple key switchassemblies further comprises a mounting guide that is assembled into arespective second opening to mount the given key switch assembly to thePCB with the light conductive structure of the given key switch assemblyextending from the key switch chassis housing through a respective firstopening defined in the PCB adjacent to the respective second opening. 8.The system of claim 5, further comprising a substantially planar lightreflective film having a plane oriented in substantially parallelrelationship with a plane of the light spreader component, the lightspreader component being disposed between the PCB and the lightreflective film.
 9. The system of claim 1, comprising digital signalcircuitry configured to provide an on/off digital output signal when thedepressable key component is depressed downward by a predeterminedextent.
 10. An information handling system including the keyboardassembly of claim 9, comprising: at least one host processing deviceconfigured to execute a user application thereon; and a keyboardassembly according to claim 9; where the keyboard controller isconfigured to process the on/off digital output signal and to providethe processed digital key information based on the on/off digital outputsignal to the host processing device.
 11. The system of claim 1,comprising variable displacement-sensing circuitry configured to detectdisplacement of the depressable key component relative to the key switchchassis housing and to provide one or more variable displacement signalsthat vary in character based on the amount of displacement of thedepressable key component between the extended position and thedepressed position, or a combination thereof.
 12. The system of claim 1,comprising each of digital signal circuitry configured to provide anon/off digital output signal when the depressable key component isdepressed downward by a predetermined extent; and variabledisplacement-sensing circuitry configured to detect displacement of thedepressable key component relative to the key switch chassis housing andto provide one or more variable displacement signals that vary incharacter based on the amount of displacement of the depressable keycomponent between the extended position and the depressed position, or acombination thereof.
 13. A spring loaded mechanical key switch assembly,comprising: a key switch chassis housing having a first end and a secondend; a depressable key component movably received within the key switchchassis housing and having a first end and a second end, the first endof the depressable key component being movable between an extendedposition and a depressed position relative to the first end of the keyswitch chassis housing with the first end of the depressable keycomponent being closer to the first end of the key switch chassishousing in the depressed position than in the extended position; aspring element configured to provide a resilient force to resistdownward movement of the depressable key component from the extendedposition to the depressed position; at least one of digital signalcircuitry configured to provide an on/off digital output signal when thedepressable key component is depressed downward by a predeterminedextent, variable displacement-sensing circuitry configured to detectdisplacement of the depressable key component relative to the key switchchassis housing and to provide one or more variable displacement signalsthat vary in character based on the amount of displacement of thedepressable key component between the extended position and thedepressed position, or a combination thereof, and at least one lightconductive structure having first and second ends and extending from thesecond end of the key switch chassis housing to the first end of the keyswitch chassis housing, the first end of the light conductive structurebeing positioned adjacent the first end of the key switch chassishousing and the second end of the light conductive structure beingpositioned adjacent the second end of the key switch chassis housing;where a second end of the light conductive structure is positioned toreceive light from the light spreader component; where the lightconductive structure is configured to conduct light received from thelight spreader to the first end of the light conductive structure; andwhere the first end of the light conductive structure is configured toemit the conducted light from the first end of the light conductivestructure.
 14. The key switch assembly of claim 13, where thedepressable key component further comprises a keycap on the first end ofthe depressable key component; where the light conductive structurecomprises a light pipe; and where the keycap comprises a top surface andan underside surface opposite the top surface, the underside surface ofthe keycap facing the first end of the light conductive structure toreceive the light emitted therefrom, and the top surface of the keycapfacing upward toward a user; where the keycap further comprises one ormore light transmissive features extending through the keycap from theunderside surface to the top surface of the keycap such that lightemitted from beneath the key cap by the light conductive structure isvisible by a user from above the key cap through the light transmissivekey features.
 15. The key switch assembly of claim 14, where the lighttransmissive features comprise at least one of a laser etchedalphanumeric character, a laser etched key cap rim, an aperture definedin the keycap, a transparent or translucent keycap material, or acombination thereof.
 16. The key switch assembly of claim 13, comprisingdigital signal circuitry configured to provide an on/off digital outputsignal when the depressable key component is depressed downward by apredetermined extent.
 17. The key switch assembly of claim 13,comprising variable displacement-sensing circuitry configured to detectdisplacement of the depressable key component relative to the key switchchassis housing and to provide one or more variable displacement signalsthat vary in character based on the amount of displacement of thedepressable key component between the extended position and thedepressed position, or a combination thereof.
 18. The key switchassembly of claim 13, comprising each of digital signal circuitryconfigured to provide an on/off digital output signal when thedepressable key component is depressed downward by a predeterminedextent; and variable displacement-sensing circuitry configured to detectdisplacement of the depressable key component relative to the key switchchassis housing and to provide one or more variable displacement signalsthat vary in character based on the amount of displacement of thedepressable key component between the extended position and thedepressed position, or a combination thereof.
 19. A method of operatingone or more key switch assemblies, comprising: providing at least onespring loaded mechanical key switch assembly, comprising: a key switchchassis housing having a first end and a second end, a depressable keycomponent movably received within the key switch chassis housing andhaving a first end and a second end, the first end of the depressablekey component being movable between an extended position and a depressedposition relative to the first end of the key switch chassis housingwith the first end of the depressable key component being closer to thefirst end of the key switch chassis housing in the depressed positionthan in the extended position, a spring element configured to provide aresilient force to resist downward movement of the depressable keycomponent from the extended position to the depressed position, at leastone of digital signal circuitry configured to provide an on/off digitaloutput signal when the depressable key component is depressed downwardby a predetermined extent, variable displacement-sensing circuitryconfigured to detect displacement of the depressable key componentrelative to the key switch chassis housing and to provide one or morevariable displacement signals that vary in character based on the amountof displacement of the depressable key component between the extendedposition and the depressed position, or a combination thereof, and atleast one light conductive structure having first and second ends andextending from the second end of the key switch chassis housing to thefirst end of the key switch chassis housing, the first end of the lightconductive structure being positioned adjacent the first end of the keyswitch chassis housing and the second end of the light conductivestructure being positioned adjacent the second end of the key switchchassis housing, the light conductive structure being configured toconduct light from the second end to the first end of the lightconductive structure; where the first end of the light conductivestructure is configured to emit the conducted light from the first endof the light conductive structure; and providing light to the second endof the light conductive structure to cause the light conductivestructure to conduct and emit the light from the first end of the lightconductive structure.
 20. The method of claim 19, where the depressablekey component further comprises a keycap on the first end of thedepressable key component; where the light conductive structurecomprises a light pipe; where the keycap comprises a top surface and anunderside surface opposite the top surface, the underside surface of thekeycap facing the first end of the light conductive structure to receivethe light emitted therefrom, and the top surface of the keycap facingupward toward a user; where the keycap further comprises one or morelight transmissive features extending through the keycap from theunderside surface to the top surface of the keycap such that lightemitted from beneath the key cap by the light conductive structure isvisible by a user from above the key cap through the light transmissivekey features.
 21. The system of claim 19, further comprising: providingmultiple spring loaded mechanical key switch assemblies; and providinglight to the respective second end of the light conductive structure ofeach of the multiple spring loaded mechanical key assemblies using atleast one common light source to cause the light conductive structure ofeach the multiple mechanical key switch assemblies to conduct and emitthe light from the respective first end of the light conductivestructure of each of the multiple spring loaded mechanical keyassemblies.